Week 1 - F(2) - Microbiology Practical Tutorial (Labs)

Question 1

1. A 28 year old man attends the Sexual Health clinic complaining of pain when he passes urine and a purulent urethral discharge. What do you think the diagnosis may be already?

Answer 1

Neisseria gonorrhea

Question 2

You take a urethral swab for microscopy (done at the clinic) and bacterial culture and a “first pass” urine for combined chlamydia and gonococcal PCR . You are provided with a Gram stained film of the urethral discharge made in SRH clinic What does the gram stain show?

Answer 2

The gram stain shows a gram negative intracellular diplococci

Question 3

(b) What diagnosis does this Gram film result suggest? (c) What treatment would you give this patient for this infection?

Answer 3

Diagnosis suggestive of Neisseria Gonorrhea Give this patient IM ceftriaxone + Oral azithromycin

Question 4

Why is the oral azithromycin given?

Answer 4

Oral azithromycin co-treats the gonorrhea and helps to prevent resistance against ceftriaxone emerging Oral azithromycin is also protective against a potenital chalmydia infection

Question 5

d) Gonorrhoea (and Chlamydia) are diagnosed these days primarily by PCR (NAATs) testing. What are the advantages of using this type of test instead of culture?

Answer 5

The NAAT testing is much quicker (takes hours instead of days) It is highly specific and sensitive to the organisms The test can test organisms that have died and therefore does not need to be carried out in the SRH clinic The test also requires a less invasive swab to be taken

Question 6

(e) What is the main disadvantage of using PCR testing for gonorrhoea?

Answer 6

The test cannot test antibiotic sensitivities as unable to culture Also cannot test of cure for organisms until after 5 weeks as the test will detect dead organisms

Question 7

(f) Patients attending the Sexual Health clinic are offered tests for a range of sexually transmitted infections. What other infections do you think the clinic would test for in this patient? (g) The patient is given an appointment to return to the Sexual Health clinic 12 weeks after the date of his visit to Amsterdam. Why?

Answer 7

Test for chlamyida, gonorrhea, HIV, Hep B, Syphilis 12 weeks post amsterdam will be able to test for HIV

Question 8

Case 2 A 19 year old woman attends your GP surgery complaining of vaginal discharge and intense vulval itch which she finds very uncomfortable.. You take a high vaginal swab for culture and the organism shown (Gram film and culture) is isolated. What is this?

Answer 8

This is organism is candida (albicans) can see the hyphae and budding of the yeast organism

Question 9

She had unprotected sex 2 weeks earlier at a party with a new partner, but she is taking oral contraceptives. She is worried that she may have picked up some sexually transmitted disease from her new boyfriend. On examination, the vulva is very red and inflamed and there is a thick white discharge What is the casual organism and what is the treatment?

Answer 9

The casual organism of the vaginal candidiasis is candida albicans Treatment would be to give the patient Oral fluconazole + clotrimazole cream Clotrimazole pessary + clotrimazole cream

Question 10

d) Should her boyfriend be treated too? (e) What other advice do you give her?

Answer 10

Boydirend should only be treated if he has symptoms as candida most commonly is not sexually transmitted Candidia reinfections are common

Question 11

(f) What specimen would you (the GP) also have been taken from this patient to check for chlamydia and gonorrhoea and why would you ask her for a contact telephone number?

Answer 11

The GP would have taken a swab for NAAT testing (not for culture as the SRH clincs carry out culture as the organisms need to be tested immediately) Get telepjone number in case you have to call the patient to tell her off the results

Question 12

Case 3 A 26 year old lady attends the gynaecology clinic complaining of a yellowish vaginal discharge. A HVS is taken and submitted to the laboratory. The laboratory sees the organism shown moving about on microscopy. (a) Describe what you see.

Answer 12

Can see a protozaoal infection - the flagellae is there to help with movement of the protozoal infection

Question 13

(b) What is this organism seen on microscopy? (c) How has the patient acquired this infection?

Answer 13

The organism is trichomoniasis vaginalis Patient has acquired the infection via sexual transmission

Question 14

Why is the organism shown on microscopy not bacterial vaginalis? (which organism cause bacterial vaginalis) How is bacterial vaginalis transmitted?

Answer 14

Bacterial vaginalis is caused by gardnerella vaginalis This is a gram variable staining bacteria It is not transmitted and instead is due to a change in the normal vaginal flora

Question 15

(d) What treatment would you give to treat the trichomoniasis vaginalis? This also treats bacterial vaginosis (e)Should her partner(s) be treated too?

Answer 15

Would give oral metronidazole The patients partner should be treated too

Question 16

Case 4 - A 28 year old woman visits her GP.. She has had several attacks of a similar nature in the past two years. The lesions start as small blisters, i.e. vesicles and then become pustular. They are exquisitely painful and the vulva is inflamed: she also has difficulty passing urine. The attacks last about two weeks and then resolve. The patient is sexually active and her general health is good. What is the diagnosis of the patient? What are the clssical symptoms?

Answer 16

This patient has genital herpes Several attacks, difficulty passing urine, starts as blisters before ulceration

Question 17

(b) What is the likely infectious agent? (c) What specimen would you take to confirm the diagnosis?

Answer 17

Likely infectious agent would be HSV-1 or HSV-2 Would deroof a blister and take a swab and send on viral transport medium for PCR testing

Question 18

(d) Why is it important to confirm the diagnosis? (e) Name one antiviral therapy available for this condition.

Answer 18

This condition is highly transmissible and therefore important to confirm diagnosis - can also badly affect the immunocompromised One antiviral therapy for this is acicylovir

Question 19

What is the most common viral STI in the UK?

Answer 19

Most common viral STI would be human papilloma virus

Question 20

Case 5 A 35 year old man has developed these lesions over a period of about 18 months. His girlfriend insisted he see a doctor because she “won’t have sex with a cauliflower”. An illustration of the condition is provided. (a) What are the lesions?

Answer 20

These are genital warts

Question 21

Are the lesions in genital warts usually painful?

Answer 21

The lesions are not particularly painful or tender Can be tender when wearing tight underpants and the skin becomes chafed.

Question 22

(b) Which virus causes genital warts?

Answer 22

Human papilloma virus causes genital warts HPV types 1-4 warts/verucas HPV types 6&11 causes genital warts HPV types 16&18 causes cervical cancer

Question 23

(c) Will sending a swab of the lesions for viral culture help to confirm the diagnosis? (d) Is the girl just fussy or does she have reason to worry about herself?

Answer 23

Sending a swab wil help yes The girl has a right to worry as HPV is a major cause of cervical cancer

Question 24

What treatment is available for the HPV lesions on the mans penis? Which treatment can be used on all anogenital warts for HPV?

Answer 24

Podophyllotoxin (warticon) - this is a cytotoxic therapy Inquimodi is also an availabe treatment - inquimoid can be used on all anogenital warts Cryotherapy is also a treatment - may require repeat treatments

Question 25

e) - Is there a vaccine available to recude the risk of HPV infection? If so, then which types of HPV? Who recieves the vaccine?

Answer 25

HPV vaccine known as gardasil - prevents against HPV types 6,11,16 and 18 Females aged 11-13 and MSM below the age of 45 get the vaccine (the vaccine used to be known as cervarix and only protected against HPV 16 and 18)

Question 26

Case 6 A 30 year old man attends your surgery with an ulcerated lesion on his penis (picture provided). The lesion is not particularly tender to touch. You can feels enlarged lymph nodes in both groins. The patient has been working in Thailand for the last 6 months where he had unprotected sex with a girl in a bar on several occasions. You refer the patient urgently to the Sexual Health clinic. (a) Suggest 2 possible causes of genital ulceration

Answer 26

Syphilis Lymphogranuloma venereum (LGV) Herpes simplex virus (HSV)

Question 27

What chalmdyia serovars are lymphogranuloma venereum? What is the treatment for this?

Answer 27

Serovars L1-L3 Doxcycline for three weeks Rectal chlamydia treatment is doxycycline as well - response to doxycycline is better than azithromycin for rectal

Question 28

Case 6 A 30 year old man attends your surgery with an ulcerated lesion on his penis (picture provided). The lesion is not particularly tender to touch. You can feels enlarged lymph nodes in both groins. The patient has been working in Thailand for the last 6 months where he had unprotected sex with a girl in a bar on several occasions. You refer the patient urgently to the Sexual Health clinic. (b)What is the most likely diagnosis in this patient?&why?

Answer 28

Most likely diagnosis is syphilis The patient has a painless ulcer and enlarged lymph nodes Likely to be primary syphilis - the chancre

Question 29

(c) What specimen(s) would you send to the microbiology laboratory in order to confirm the diagnosis?

Answer 29

As it is the primary chancre - antibodies may not have formed and therefore a swab of the lesion sent for PCR

Question 30

What is the causative organism in syphilis? (e) What antibiotic treatment would you suggest for this patient?

Answer 30

Causative organism is treponema pallidum Treatment would be IM penicillin

Question 31

(f) Six months later, you re-test the patient, and you receive the second lab. report back. Patient has a negative VDRL after 6 months and negative IgM Has this patient been adequately treated? (g) Would you suggest that this patient has tests for any other infections, and if so, which infections?

Answer 31

As the patients IgM and VDRL have come back negative, the patient has been adequately treated These are specific serological tests Would check for Chlamydia, Gonorrhea, (Syphilis already tested), HepB (maybe C) and HIV

Question 32

If a patient presents with a diagnosis of an STD, what other STD is imperative to always be checked for?

Answer 32

Always check for HIV